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Xavier

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About Xavier

  • Rank
    Meson

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  • Location
    Newcastle-Upon-Tyne
  • College Major/Degree
    University of Newcastle-Upon-Tyne
  • Favorite Area of Science
    All
  • Biography
    I am a graduate in physics and chemistry, which naturally led me to a career in biochemistry. I have recently begun a PhD in Biomedical Nanotechnology. My heroes are Richard Feynman and Richard Dawkins.
  • Occupation
    PhD student
  1. Humans do spontaneously combust under certain conditions - after an initial external ignition. The body acts as an inside-out candle with the bodyfat acting as the wax and clothing as the wick (http://en.wikipedia.org/wiki/The_wick_effect). You need only to hypothetise that the spark ignites a scrap of cloth which burns slowly enough to melt the fat above it suffusing the cloth with a fuel that it will burn and replenish for hours.
  2. A general term for creatures, particularly single celled one that live in extreme conditions is 'extremophiles' - might be worth typing into Google. Take a look at the differences between polar bears and ordinary brown bears from warmer climes - this has been in the science news recently. You might investigate the Notothenioids, such as the arctic cod. You should look up 'Black Smokers', hot vents on the ocean floor and the source of Taq polymerase, an enzyme that has revolutionised molecular biology for reasons related to this subject. An interesting way to kick off your research might be to read about what lifeforms might survive in the cold wastes of Mars or elsewhere - 'Exobiology' Perhaps you could even look at some of the ideas behind 'Panspermia', the theory that all life on earth was seeded by lifeforms that have survived the cold depths of space of eons. Or just consider what the difference is between coniferous and deciduous trees and between succulents and broad leafed plants, between reptiles and mammals and between africans and europeans.
  3. If you are in a three storey building. Fill a narrow hose with water and attach one end to the apparatus and a tap to the other. Dangle the other end out of a window, walk downstairs and open the tap letting the water drain out carefully so that air cannot get in. If the hose drops more than 35m the last bit of water should be held in the hose by the vacuum above it (If the drop is less than 35m you can turn off the tap before the water is drained out and achieve a partial vacuum) The more vertical the hose, the better and a narrowing of the end with the tap to get a fast outflow as there is less chance of air getting into the hose as the water drains. Another classic way of whipping up a 'quick and dirty' vacuum is to heat a vessel with a little water in the base so the steam displaces most of the air. The vessel is then sealed (or attached to apparatus) and allowed to cool. As the steam condenses it makes a decent partial vacuum which is maintained for some time as, if the pressure increases more of the steam condenses. You need a strong vessel, though, And finally, A really dirty method I used for degassing small quantities of buffers (very effectively, I might add). If you are in a bio lab you probably have access to 60mL plastic syringes with luer fittings (from Beckton Dickinson etc). If you can arrange apparatus such that the syringe is connected to the apparatus with no air in the system you can draw back the syringe and create a pocket of vacuum inside the barrel (It takes some strength. Shove AA batteries or similar between end of plunger and rim of barrel to hold it). Once you have applied the correct temperature to your distillant for a while you will have a syringe full of distillate to condense as you like. These syringes can hold >15 bar of pressure and seem to hold a vacuum for at least several minutes and the luer fittings are held on all the more tightly with the low pressure (At high pressures they tended to burst off at inopportune moments)
  4. OF COURSE committing a sexual act with a partner outside a relationship is 'cheating'. In so far as there is a definition of cheating, that is it. It strikes me that your girlfriend is playing fast and loose with semantics for the advantage of her gender. Firstly, 'cheating' implies a rule of agreement that is secretly broken, but there is no actual agreement in most cases. Even the marriage ritual doesn't explicitly say, especially now that vows and mere wordy protestations of love where they once were a set list of promises. (NB If a woman does not want to vow to love, honour and OBEY then she does not want to get married because that is what marriage is!) The only rule is in essence the one I started with but it doesn't define what constitutes a sexual act. Examples can be placed for any activity except actual penile penetration that clearly are not sexual acts. For example, kissing your mother or the bride at her wedding or the nearest policewoman on a drunken New Years Eve; having a massage; stripping off for a medical examination. None of these are cheating so, for example, kissing cannot be called cheating without several exemption clauses. Where there clauses come from becomes the issue. Some might say that your intent is the defining factor, but what of these cases: You find yourself attracted to the doctor who is performing your pelvic examination. You are aroused domination - as many are - and you find that being told off by a policeman for some driving offence illicits an emotional reaction. Have you cheated. Would it be cheating if you allowed the exam to continue once you had realised your hidden desire but kept it hidden. In the latter case, were you actually being sexually assaulted against your will by the policeman? With the exception of a definitive physical act of penile penetration, the only functional definition of 'cheating' is that the partner decides, after the fact that they feel cheated. Other physical acts are not definitive, nor are the desires of the cheater. The point of this is that there is no equivalent of penile penetration between female homosexuals. Hence the special pleading for lesbians which dates back, at least to Queen Victoria who (it is said) insisted that a law criminalising homosexuality had any mention of female homosexuality removed. You marriage, and your heart will be just as broken, though, whether she runs off with a woman or a man. PS. Regarding the polarisation of gender preference in the population. My personal view is that there is a continuum, heavily skewed towards heterosexuality but that no-one is completely gay or straight. Note the activities of prison inmates when there is no partner of the preferred gender available. However, there is a huge cultural filter on the expression of, or even the consideration of same sex intercourse that modulates the apparent opinions and desires of the population. I am wont to think that the filter is overwhelmingly a male homophobic prejudice and that this filter is a small part of the power/influence relationships that women develop, little more than a mutual agreement to keep sex 'off the table' as, as a mechanism for establishing dominance it takes too much time.
  5. This is to miss the historical context of Marx' philosophy. At the end of the nineteenth century in England, after the age of enlightenment and at - apparently - the height of civilisation it was generally supposed that humans, or at least strong-willed white, male, european imperialists had already reached the point of enlightened altruism. Science seemed to be well on the way to explaining everything, including society. Through the enlightened altruism of the treatment of the obviously inferior natives of Africa and the Americas, through the obvious comfort and prosperity of all Englishmen (well, all the ones that mattered) it seemed that the old heirarchical systems were holding us back from a next utopian step. The poor and dispossessed should have been the happiest with the new order as they gain the most. Once they see it working, they will also see the enlightenment and be happy to support it. For the better off, who might have more to lose, their intelligence would be advanced enough for them to see that whilst they lose relative position, they nevertheless gain in absolute terms through living in peace and harmony. Blue_crystals original post demonstrates with eponymous clarity that the last point was just plain wrong. Even allegedly intelligent people find reasons to want life to be a zero-sum game; As Attilla the Hun may have actually said,.. "It is not enough that I succeed, others must fail!" Furthermore, they are correct. The problem is that the logic behind the mutually altruistic philosophy is that "what goes around, comes around."; - if you break the rules, eventually you will get your comeupance. But, eventually could be a long time coming and we are all mortal. It is quite likely that if we break only a few rules and only occasionally then we will be safely in our graves before the we push our luck too far. This, then is the best strategy to adopt, though everyone has their own judgement about where the risk/reward line is drawn. It may be that you drive too fast sometimes, or drive whilst intoxicated once or twice. The chances are that you won't kill anyone and lose out big, or even get caught and fined. Alternatively you may knock over post offices for a living, if you consider the risk vs. reward to be in your favour (which it may if the alternatives are a life of drudgery and poverty vs. a life of excitement and respect and wealth, if you dont get caught.) In either case, eventually you will be caught and the punishment meted out, whether by nature or by society and this, theoratically, negates any accumulated advantages from your successes. But, you can hope that you will never be caught - quite likely if you are looking to avoid killing yourself or someone else whilst driving dangerously, less likely if you are a bank-robber, but the rewards are greater. And as for sex; primary almost the beliefs in the new, enlightened humanity is the notion that we can finally remove this vile, divisive and inhuman drive to compete for mates in the visceral, animalistic way of our ancestors. Instead, we would overcome our base desires by using our minds and deciding when, how and who should have sexual relations - the decisions need not be clinical or based only on efficient procreation, but merely on pairing up in such a way as to allow the maximum satisfaction for the maximum number. To many this last probably sounds ridiculously naive, even unpleasant. You are too vested in the present system and too controlled by your genes. The victorians certainly had a rosier picture of the power of the human mind to take control of its host body (and a lack of input from females, in whom these relationships are vastly more complex than the male passions.) It is quite possible, though. After all, we (mostly) don't rape, even if we could get away with it. You (mostly) all lie and cheat to get mates (cosmetics, buying flowers, 'chat-up' lines etc.) and don't think that that it lying at all. You also knowingly lie and cheat (feigning interest, exaggerating the importance of your work etc.) but excuse it as good manners and 'white' lies. Not to have good manners, in the zero-sum world, means you are ill-mannered; thus truth is a bad thing. If only the entire population could simultaneously come to this conclusion and act upon it then your date would know he is being dull and stop - without being insulted - and either find a more interesting topic or a more receptive date. Marriages would not crumble after a few years as the partners finally find out what they are really like, when there is no big house in the suburbs and she looks terrible with short hair and no make-up. The worst problem is that the current system is evolutionarily stable. Those of us whose predilection is for enlightenment are less likely to mate as the likeminded are few and far between, so they only become fewer as the generations progresss. Similarly, ideas like those of Marx blossomed briefly in the nineteenth century and perhaps even almost gained 'critical mass' (Marx, apparently, believed that Britain or Germany were the most likely countries to convert to the communism way of life - they were the most cultured and educated places.) Nowadays, society is bulwarked against any fundemental change and speaking out in favour of such a change lessens your credibility with others such that further gesticulations are more likely to be ignored. Fortunately, the internet does allow those who want to hear this sort of rhetoric to band together and the rest of the world is, for the moment, happy to allow small groups to exchange radical ideas without becoming outsiders. The Pilgrim Fathers had to flee to the Americas for the same freedom.
  6. It is said that whilst 10% (very approx) of men over the age of 80 will die of prostate cancer, 90% will die with prostate cancer. This particular cancer varient is ubiquitous but so slow growing that a sufferer will mroe than likely die of something else before the prostate trouble becomes noticable. This was of issue when means of screening the male population for prostate cancer as cervical cancer is screened. The official line on why this screening program has not been started ( in the UK, at least) is that the tests are not yet sufficiently predictive and cost effective but the real reason has more to do with the fact that the treatment would only extend life for a year or so, on average. It has been estimated (though 'guessed' might be a better word) that a typical person has around 10 'precancerous growths' - cells that would have the capacity to become symptomatic if allowed to continue- during their lifetime. They are the sorts of things that get picked in well-person whole body scans and then have to be treated with chemo, surgery etc. even though most of them would be neutralised by the immune system without the patient ever knowing about them.
  7. I would suggest that humans did not swap strength for precision, but for endurance: 'Monkeys' live in trees where explosive movement over short distances was useful. Humans 'came down from the trees', grew taller and changed the angle of their pelvis so they could run efficiently over longer distances over empty ground. It has been suggested that our ancestors hunted by by endurance, like a wolf pack rather than with explosive speed, like a lion. This seems to fit with our upright posture for a vantage point, efficient running style and increasing intelligence. As weight carried is an important limit to endurance, upper body strength would be limited with respect to our tree-dwelling cousins for whom greater strength would mean greater short term speed. The chimp might win at arm wrestling but the human would win a marathon.
  8. Sulphide compounds (hydrogen sulphide and mercaptans/thiols) are produced by bacteria as they break down proteins so the smell warns that meat has gone off. There is also some in faeces from the meat processed in your gut so the smell would warn against that potentially infectious material. NB. Most people have populations of bacteria in their gut that make use of the sulphur in digested proteins but dedicated vegetarians tend to lose these as their diet is low in cysteine and methionine-containing proteins. However, should they eat a hearty plate of, say, baked beans the sulphur in that cannot be processed and is excreted principally as hydrogen sulphide making really smelly farts!
  9. I don't think this dolphins mutation can be written off as a re-asserted ancestral trait. The rear appendages are definitely flipper-like though smaller, but what are they attached to inside the body. This picture of a dolphin skeleton shows that there is almost no pelvis or associated structures. The dolphin would have had to retain the DNA code for all these parts for 30-40 million years of significant morphological change accurately enough that a couple of mutations would allow the whole structure to to take its place in the dolphins body without gross-probably fatal- malformation. I think that an xray of the dolphin is more likely to show a second set of vestigial shoulderblades and forearms due to an embryological accident. A rare event to be sure, but so long as the additional structures were behind the abdominal cavity it is more feasible that a working body would be produced. All the bones, nerves, muscular etc would grow according to the normal DNA instructions but from a starting point further down the spine. The lack of anchoring points for muscles that would normally attach to the ribcage would make the additional arms weak and reduce the flexibility of the dolphins spine and the whole assemblage would be smaller as it is further away from the source of nutrients, growth factors etc. Of course it could be the evolution of a new species of which this is the first we have seen if there were some very strong evolutionary pressure for, say extra manouverability to avoid fishing nets...
  10. Oral vaccines have not done well against HIV or Hepatitis B; they are both good at hiding from the immune system, HBV in the liver where too much detritus congregates and HIV in the immune system cells themselves. HIV in particular is a wily foe that evloves rapidly enough to counter targeted vaccines within an individual body (It is almost true to say that no two AIDS sufferers have genetically indentical HIV infections). I suspect that this tomato vaccine is using a scatter-gun approach, throwing large numbers of different haptens at the immune system to the hope that enough will illicit a contemporaneous immune response to provide protection against the initial viral innoculation - when viruses are most vulnerable. The trick is in finding a means of cheaply providing a concentrated, complex mixture so if the GM tomatoes can do this, fine. However a multi-target vaccine won't be very efficient so the actual protection could be patchy. If higher dosages than is typical for vaccines are to be given to improve efficiency (as I suspect was given to the experimentors' mice, due to the reported existence antibodies on mucosal surfaces - it is a rough ride for a protein fragment from the stomach all the way to such peripheral areas, few fragments would make it.) the chances of allergic reaction or other unknown sensitivities to arise. If my suspicisions are correct I consider it doubtful that FDA approval would be forthcoming, though considering the ravaging of Africa, it might be well worth the small risk of side-effects for any sort of protection against AIDS if it is affordable. And the North/South divide opens just a little further...
  11. I have read through Ms Roughgardens paper in Science 311(5763) p965 17/02/2006 because I wanted to see whether she really did not understand evolution. I am glad to say that that is not the case but, as all too often happens with evolutionary biology, she has decided to take a swipe at Darwin and get a bit of extra publicity. In this case, Darwin's ideas about sexual selection were very primitive, the Law of Evolution was pretty new then - and there is a slightly Victorian attitude about it but the implication that the notions behind sexual selection haven't moved on since then is disingenuous. Her supporting references are from 1871, 1938, the times literary supplement and Elle magazine plus her own book and one contemporary source - if you want to say Charles Darwin is wrong you've got to do better than that. Whats wrong with her 'new' theory is that it is implicit in sexual selection: There are two points worthy of mention. The first is in this quotation from the paper "We think that the notion of females choosing the genetically best males is mistaken. Studies repeatedly show that females exert choice to increase number, not genetic quality, of offspring and not to express an arbitrary feminine aesthetic." The authors have transmuted 'best male' into 'highest genetic quality male'. The best male is the one that will chaperone the largest number of copies of the females genes into future generations. Whether it is because he is the brawniest or the most likely to be a good father are equally relevant. The idea of 'choice' here is a metaphor. The authors were not trying to suggest that the parents were making an informed decision based on reasoning - i.e. and that there was no evolutionary basis to the selection. The choice represents the preprogrammed behaviour handed down by generations of users of that successful behaviour. Only the best choice will be made as the 'choosers' of any other behaviour will not have produced heirs (given a stable environment) The last three words seem to be supported by a piece of purple prose abstracted from another book and they are out of place in a theory about evolutionary selection. The second point is from the conclusion of the paper "The key elements to social selection are: (i) Reproductive social behavior and sexual reproduction are cooperative. Sexual conflict derives from negotiation breakdown. In sexual selection, sexual conflict is primitive and cooperation derived, whereas in social selection sexual cooperation is primitive and conflict derived. Hence, sexual selection and social selection are mutually exclusive theories." Conflict and cooperation are deemed to be mutually exclusive but that is only true in the case of a zero-sum game. The individuals, either male or female may or may not be in conflict but their objective never is achievable solely by beating the other. Whether objectives of the sexual partner of an individual (to get their genes into the next generation) is helped or harmed is irrelevant to the objective of getting your genes there, and it is those genes that carry the behaviour that got them there. Some of the reasons for making the purely selfish choices that go to form a tremendous variety of sexual stratagems are nicely explained in the paper and the worst that can be said of sexual selection is that it can be, and very frequently is oversimplified into strong, promiscuous males and cautious, home-making females especially in the popular media. Perhaps it is the continual drawing of this analogy with human nature that does not sit comfortably.
  12. This apparent problem with evolution stems from the argument that cells are the ultimate building blocks of all life and that even the simplest possible cell that could perform the basic functions of gathering nutrients and reproducing is still a fairly complex machine. Since life cannot exist below the cellular level, says the creationist, the simplest possible cell must have spontaneously accreted before evolution had anything to work on. This is really a simplification of Michael Behe's theory of Irreducible Complexity, repackaged so that non-biochemists can grasp it. The cell is not the ultimate building block of the evolutionary process; whether it is the ultimate building block of life is a basis for a definition of life and it is no limit to evolution. A item does not have to be 'alive' by any definition to be effected by natural selection, so long as it has the three requisite properties, felicity, fidelity and fecundity. (i.e. it makes accurate copies of itself and it can affect its own relative success in making those copies) There are several just-so stories about how a chemical soup could have gained these properties and then used them to selectively evolve into cells without any step having an outrageous improbability - there is no great body of evidence for any of them but there is no reason to believe that none of them (or a similar mechanism) was the way life really began. Michael Behe's suggestion lies heavily in the idea that such just-so stories are put-up jobs, twisting reason and credulity to fit the information that is known. Whether you feel that in such a circumstance God is a more reasonable answer or an even more ludicrous fracturing of reality really just depends on whether you were sufficiently effectively brainwashed as a child.
  13. It’s as if the golden age of hairdressing discoveries died after WWII. Instead, 50 years of Hoboken Hair Sylists Institute failures to produce fusion energy, fuel cells, etc. to replace the needs for oil are tragic proof of Dyson’s charges against scientist’s ethics that have failed to protect and preserve Humanity ever since WWII. Failures to heed Eisenhower’s warning for over 45 years is the number one reason that we have still not replaced the need for oil, thus the reason for today’s oil wars, worldwide terrorism, and sectarian warfare that threatens to spread throughout the Middle East. Thus, the greatest tragedies caused by American hairdressers due to their cultural failures to replace the need for oil after over 50 years of research into fusion, fuel cells, etc, are: 1) American hairdressers are totally unable to stop global warming, and 2) American hairdressers are totally unable to prevent escalating international chaos from overwhelming humanity.
  14. Declaration of interests: I am not a home hobbyist I work in an academic laboratory I have, in the past, considered my work to put me at (slight) risk form animal rights activists of the sort who plant parcel bombs and car bombs. 1.) There is no clear mention of prevention of terrorism in the announcement that began this discussion. A CPSC press release states that "The U.S. Consumer Product Safety Commission is charged with protecting the public from unreasonable risks of serious injury or death from more than 15,000 types of consumer products under the agency's jurisdiction." and "The CPSC is committed to protecting consumers and families from products that pose a fire, electrical, chemical, or mechanical hazard or can injure children." 2.) The connection between this issue and the rights to bear arms, smoke cigarettes and consume alcohol are that they are all potentially dangerous to others. The balance between personal freedom of action and risk of injury to others is at issue. In each case the merits and risks are debatable but the debate itself is clearly necessary. 3.) Home hobbyists in chemistry are not being singled out or victimised. As there are those with a cavalier attitude to home chemistry and others who deliberately use home chemistry for terrorist activities (NOT organised groups like Al Qaeda, but certainly individuals who try to blow up abortion clinics or who murdered a vivisectionist at the Porton Down Research Establishment in the UK a few years ago with a car bomb) there is a good argument for restricting access. A reasonable argument for allowing the continued access to potentially dangerous chemicals despite the risk is needed. By way of analogy, after a high profile school shooting in Scotland the UK government tightened the law on firearm ownership. A casualty of this popular move was that battle re-enactment hobbyists would no longer be allowed to operate their muskets (muskets were licenced as shotguns, which licences had prevoiusly been readily granted). The re-enactors were able to claim that they were strongly self-policing, that training was provided, and insisted upon before their members were allowed the handle the weapons and that the use of the weapons, including firing them had a benefit to society in general as a part of both historic and educational activities. They were also able to point out that the muskets fired only powder, not bullets and so were not explicitly being used in their capacity as dangerous weapons. After some debate, some special case exceptions were made in the law that allowed the re-enactors to continue to use their muskets much as before. Only if home chemistry hobbyists could make similar claims, particularly for effective self-policing and for some sort of general benefit to offset the residual risks could the rest of us seriously consider your wants. 4.) Establishment laboratories are almost overwhelmed with health and safety issues, risk assessments and audits. In my academic laboratory any order I place must be countersigned by the lab manager and a safety officer and I must submit a risk assessment for the use to which I will put all chemicals and often a COSSH statement - for something like potassium phosphate (I am required to wear a mask whilst making up my potassium phosphate buffers as any airborne powder is considered to be potentially hazardous!) This is the standard for sfaety in a state of the art facility (more or less) filled with professional scientists, sensors, alarms and safety equipment - you're not even allowed into the lab if you're drunk! The difference between this and the home hobbyist is the equivalent, in gun control, of advising that amateurs should not deliberately point their guns at their hosts face whilst shooting randomly at anything that moves - but accidents will happen. 5.) You may believe that you are not one of those gung-ho pyromaniacs who do stupid things with chemicals at home and kill people but:- a) How do you know; do you think those that are thought so b) How can the rest of us know c) How can you be sure that there will not be an unforseen reaction due to your lack of knowledge d) Could an additional factor beyond your control cause a unforseen reaction (eg contaminated water, a domestic gas leak, a car crashing into your house, a burglar/pet/surprisingly enterprising sibling) e) Could a miscreant gain acces to your stock and make use of them f) How can the rest of us be sure g) Do you have the facilities and procedures ready to mitigate any unforseen reaction Many of you can, in all likelihood, answer these questions satisfactorily -except b) & f)- and I would encourage you to. Such statements might even underpin a 'code of practice' that would be the start of a self-policing initiative. This is a Devils Advocates response; reply with a positive, reasoned rebuttal. I suggest that you do not attack the argument too strongly as the home hobbyist is greatly in the minority and not well understood by the general public. Persuade me that the above represents only half of the argument and that my reservations should be put aside.
  15. For a few years a 'robot olympics' was run in UK in which research students, engineers and a few families built contraptions to run a sprint race on legs, swim across a pool using 'animal-like' propulsion and do long jumps and high jumps. The event was filmed by the BBC and there may still be some information about it on the internet. As I recall the best high jumper was a small thing a few inches long that looked like it was made from rubber bands and lollipop sticks. The principle of the design was to arrange the sticks in a diamond shape so that all four of the corners had strong, flexible hinges. The diamond could be pushed or pulled flat (ie with one pair of opposite hinges pulled together and the other opposing pair as far apart as possible). Now, if a strong spring or elastic material is attached to the hinges that are going to be pulled far apart they will want to snap back into the diamond shape and in so doing they push the other hinges outwards and the whole thing hops. A word of warning; you can end up with a lot of energy in this thing. If one of the sticks or hinges breaks it could have your eye out. Getting strong enough but light enough materials will be your first challenge. Wood is a good starter as it often craks before snapping which releases some of the energy and is a little safer. The other challenge is how to keep the thing folded up and ready but not to jump until it is in the right position. If you can make that work, you'll have earned your prize. NB I the robo Olympics the 4" high winner jumped over 6 feet. The same group made a larger version about a foot long - it came second. Small is beautiful.
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